The Clinical Study of Synaptic Plasticity-based Lencanumab for the Treatment of Early Alzheimer's Disease

1. Age between 50 and 90 years.

2. Male or female patients.

3. Patients with MCI and mild AD.

4. MMSE score ≥20, CDR overall score of 0.5 or 1.

5. Amyloid-positive confirmed by Amyloid-PET or CSF.

6. Have a reliable caregiver to accompany the patient during study visits and supervise the use of study medication during the trial.

7. Agree to participate in the study and sign the informed consent form

1. Patients with cognitive impairment due to reasons other than AD.

2. A history of transient ischemic attack (TIA), stroke, cerebral hemorrhage, or seizure within the 12 months prior to screening.

3. A score of >17 on the Hamilton Depression Scale at screening, or any suicidal behavior within 6 months prior to screening, at screening, or at the baseline visit, as well as any psychiatric diagnosis or symptoms that interfere with the study procedure (such as hallucinations, anxiety disorder, or paranoia).

4. Patients with a bleeding disorder or receiving anticoagulant therapy, as well as any with malignant tumors, severe gastrointestinal, kidney, liver, respiratory, immune, endocrine, and cardiovascular system diseases that affect this study.

5. A hypersensitivity reaction to ranucimab or any other ingredient in the injection solution, or to any monoclonal antibody treatment.

6. Contraindications to MRI scanning, including those with a pacemaker/defibrillator or ferromagnetic metal implants (except for skull and cardiac devices approved as safe for MRI scanning).

7. A known or suspected history of drug or alcohol abuse or dependence within the 2 years prior to screening.

8. Participation in a clinical study involving any therapeutic monoclonal antibody or novel compounds for the treatment of AD within the 6 months prior to screening, unless it can be proven that the subject was in the placebo treatment group.

9. Planning to undergo surgery requiring general anesthesia during the study period.

10. A positive pregnancy test result, lactation, or pregnancy in females at screening or baseline.